PROJECT SUMMARY/ABSTRACT: Nearly 1 in every 120 children born has a congenital heart defect (CHD). While surgical therapy has improved survival, many of these children go on to develop heart failure (HF). The emergence of cardiovascular regenerative medicine as a potential therapeutic strategy for pediatric HF has provided new avenues for treatment. While primarily tried in adults, stem cell therapy is relatively untested in the pediatric population. It is thus critical to develop novel methods of exploring the regenerative potential of these cells to improve therapeutic interventions in the pediatric population. Stem cell based therapies have shown beneficial effects on several cardiovascular diseases in adults, and cardiac-derived c-kit+ progenitor cells (CPCs), a progenitor cell found in the myocardium, have met with early success in a clinical trial in adults. Due to the ability to readily isolate these cells from CHD patients during surgery, their capacity to proliferate in culture, and their ease of manipulation, pediatric CPCs serve as an ideal cell population for regenerative medicine. However, previous studies have shown that unless these cells are extracted at a very young age (<1 month) the therapeutic efficacy of these cells is diminished. With the vast majority of patients undergoing surgery for CHDs >1 month old, finding novel ways to enhance the regenerative potential of these cells would overcome this critical barrier to stem cell therapy and allow for both autologous and allogeneic treatment options in children and adults. It has been shown that the regenerative potential of adult CPCs can be enhanced by ex vivo manipulation. Electrical stimulation (ES) is one treatment known to enhance cardiogenic potential of various adult stem cells; however, the mechanism remains undetermined. Our published data show that pediatric CPCs (isolated from patients between 1-5 years of age) respond to ES by initiating calcium (Ca2+) oscillations making them an ideal population of cells for manipulation by ex vivo ES. Additionally, our data indicate ES enhances both the function and the retention of pediatric CPCs in vivo. The objective of this proposal is to examine the protective/regenerative capacity of pediatric CPCs in response to ES. We aim to characterize the paracrine factors released by ES-treated pediatric CPCs and determine their effect on cardiac cells, characterize the mechanism of enhanced adhesion/retention, and finally determine if ES enhances their function in vivo. Successful completion of this project will provide mechanisms to enhance the therapeutic efficacy of cardiac stem cells, provide autologous and allogeneic treatment options, and advance regenerative medicine. This project also directly addresses a critical barrier in stem cell therapies for pediatric HF by providing autologous and allogeneic treatments using pre-conditioned CPCs. Additionally, our preliminary data suggest our findings may be applicable as a broader therapy for other cardiac indications such as myocardial infarction. Our results will have implications on all cell-based therapies and offer valuable insights into mechanisms to enhance the therapeutic potential of stem/progenitor cells from children to adults.